Driving while high
There’s a move afoot to establish a new legal level for marijuana impairment while driving.
Good for Rep. Claire Levy, the Boulder Democrat who plans to introduce the measure in the Colorado Legislature when it convenes next month.
With growing numbers of people using medical marijuana under Colorado’s constitutional amendment that allows such use, there needs to be a clear standard for what constitutes driving under the influence of pot.
Currently police officers who suspect somebody of driving under the influence of marijuana must depend on visible signs of impairment — speech problems, poor balance, dilated eyes or other physical indications. There is not a science-based standard for how much of the intoxicant is allowed in the bloodstream, as there is with alcohol.
Levy’s proposal would set the legal limit at 5 nanograms of THC — the primary psychoactive chemical in marijuana — per milliliter of blood. That’s the same limit established in Pennsylvania, and it’s not just an arbitrary number.
It’s within the range recommended by marijuana legalization advocates and others — based on a number of scientific studies — for when THC in the bloodstream begins to affect one’s ability to drive safely.
One issue with marijuana that’s different from alcohol is the fact that some chemical indicators of marijuana remain in the bloodstream and other parts of the body long after any impairment of one’s ability to function effectively. Someone who used marijuana one day may still show evidence of marijuana use in his or her body days or weeks later.
That’s why advocates of a marijuana driving standard urge state officials to only include evidence of the active THC component, and not the inert metabolites of THC that may linger in the body for as long as 90 days. We hope Levy takes that into consideration as her bill is being drafted.
The alternative to all of this is to adopt a zero-tolerance standard for THC or its metabolites in the body, as some states have done. But that would effectively mean someone who consumes marijuana regularly for medical reasons — as voters in Colorado have said they should be able to do — would never be legally allowed to drive. That could be true even for those who use medical marijuana as prescribed by a physician, to relieve pain or other symptoms, and don’t overindulge.
Rep. Levy’s plan for a reasonable limit that prohibits driving when one’s motor functions are impaired is far more sensible for a state that has already said it’s all right for some people to consume marijuana for medical reasons.
Furthermore, the Colorado Commission on Criminal and Juvenile Justice has endorsed Levy’s plan. The Colorado Legislature should embrace it as well.